In this page you can see United States unemployment rate . United States unemployment rate.
It is the percentage that expresses the proportion of unemployed in US compared to the total active population:

United States unemployment rate = total unemployed United States / United States active population

Unemployed is a worker who don´t have a employ.

Clicking on the links in the table you can get more information.

If you want to compare USA unemployment to other countries, see unemployment.